If you discover when running Windows PE that you need additional drivers, you can add them using the Drvload command as follows:
Drvload.exe path1[,path2…]
Here pathn is the path to each driver (.inf) file separated by commas. Alternatively, you can add drivers ahead of time to your Windows PE build by using the Peimg command as described in my other tip titled "Adding device drivers offline to Windows PE".
For more information on deploying Vista, see my series of articles titled Deploying Vista on WindowsNetworking.com, and see also Part 2: Deployment in the Windows Vista Resource Kit, Second Edition from Microsoft Press.